In recent years numerous electronic push button lock mechanisms have been marketed as an alternative to conventional key and combination locks. The push button lock eliminates the problem of the lost key and enables the user to open the lock with only one hand, which can be of great practical importance when carrying packages or the like. Such electronic push button locks, however, are often complex in structure and expensive to produce. They also depend upon an electrical source which can fail leaving the lock in either a permanently locked or unlocked position. Accordingly, attempts have been made to devise mechanical or electro-mechanical locks which incorporate at least some of the advantages of electronic push button systems.
Three mechanical lock mechanisms are shown in U.S. Pat. Nos. 3,529,454, 3,040,556, and 3,027,743. These locks each employ a push button mechanism which operates through a variety of complex mechanical linkages to open a lock bolt or similar element. While constituting some improvement over the totally electronic solutions, these electro-mechanical and purely mechanical locks are still inherently complex. In U.S. Pat. Nos. 1,596,670, 1,613,550, 1,707,523 and 3,098,376 lock mechanisms are set forth which are primarily dial-type combination locks. In addition to being complex in structure, the dial combination lock does not afford the convenience of operation which accrues from a push button lock.
Accordingly, it is an object of the present invention to provide a mechanical push button lock which has a relatively simple bolt actuating structure with a minimum of moving parts and yet provides a high degree of security.
It is another object of the present invention to provide a mechanical push button lock which is extremely durable and trouble-free in operation.
Still a further object of the present invention is to provide a mechanical push button lock in which the unlocking combination of push buttons can be easily and rapidly changed.
Still a further object of the present invention is to provide a mechanical push button lock which is inexpensive to construct and can be installed easily in existing doors.
The mechanical push button lock of the present invention has other objects and features of advantage, some of which will become apparent from the accompanying drawing or are set forth in the following detailed description.